The wrong value for the false_easting for the RSO projection has been confirmed as a bug in GeoTiff: <a href="http://trac.osgeo.org/geotiff/ticket/38">http://trac.osgeo.org/geotiff/ticket/38</a><div><br clear="all"><span style="font-size:large"><i><font face="garamond, serif"><b><font color="#FF6600">Hilmy</font></b></font></i></span><br>
<br><br><div class="gmail_quote">On Thu, Apr 7, 2011 at 5:04 PM, Hilmy Hashim <span dir="ltr"><<a href="mailto:hilmyh@gmail.com">hilmyh@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>I am using QGIS 1.7.0 dev version (now at revision 15677) from the OSGeo4W suite on a Windows 7 64-bit machine.</div><div><br></div><div>The proj4 string for EPSG:3168 Kertau (RSO) / RSO Malaya (m) from Settings->Project Properties is as follows:</div>
<div><br></div><div>+proj=omerc +lat_0=4 +lonc=102.25 +alpha=323.0257905 +k=0.99984 +x_0=804670.24 +y_0=0 +a=6377295.664 +b=6356094.667915204 +units=m +no_defs</div><div><br></div><div>Note in particular:</div><div>+alpha=323.0257905 (azimuth)</div>
+x_0=804670.24 (false easting)<div>+gamma (rectified grid angle) is not defined</div><div><br></div><div>I assigned an SRS for a GeoTIFF raster using GdalTools Translate (Convert format), essentially doing a gdal_translate -a_srs EPSG:3168.</div>
<div><br></div><div>Using GdalTools->Information (gdalinfo) I get this SRS definition:</div><div><br></div><div><div>Driver: GTiff/GeoTIFF</div><div>...</div><div>Coordinate System is:</div><div>PROJCS["Kertau (RSO) / RSO Malaya (m)",</div>
<div> GEOGCS["Kertau (RSO)",</div><div> DATUM["Kertau_RSO",</div><div> SPHEROID["Everest 1830 (RSO 1969)",6377295.664,300.8017000000015,</div><div> AUTHORITY["EPSG","7056"]],</div>
<div> AUTHORITY["EPSG","6751"]],</div><div> PRIMEM["Greenwich",0],</div><div> UNIT["degree",0.0174532925199433],</div><div> AUTHORITY["EPSG","4751"]],</div>
<div> PROJECTION["Hotine_Oblique_Mercator"],</div><div> PARAMETER["latitude_of_center",4],</div><div> PARAMETER["longitude_of_center",102.25],</div><div> PARAMETER["azimuth",323.0257905],</div>
<div> PARAMETER["rectified_grid_angle",323.1301023611111],</div><div> PARAMETER["scale_factor",0.99984],</div><div> PARAMETER["false_easting",0],</div><div> PARAMETER["false_northing",0],</div>
<div> UNIT["metre",1,</div><div> AUTHORITY["EPSG","9001"]],</div><div> AUTHORITY["EPSG","3168"]]</div><div>...</div></div><div><br></div><div>Notice that the "false easting" parameter is 0 instead of the correct value of 804670.24 as found in proj4. The azimuth value is correct and there is also a rectified_grid_angle value.</div>
<div><br></div><div>Looking in OSGeo4W\share\epsg_csv\pcs.csv, I see the following values for 3168:</div><div><br></div><div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">PARAMETER_VALUE_1: </span><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">804670.24</span></div>
<div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">PARAMETER_VALUE_5: </span><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">323.01328458</span></div>
<div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">PARAMETER_VALUE_6: </span><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">323.07483685</span></div>
<div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap"><br></span></div><div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">Now the false easting value is correct, while the azimuth and rectified_skew_angle are different.</span></div>
<div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap"><br></span></div><div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap">So where is Gdal in QGis getting it's parameters from?</span></div>
<div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap"><br></span></div><font color="#888888"><div><span style="font-family:arial, sans, sans-serif;font-size:13px;white-space:pre-wrap"><br>
</span></div><div><br clear="all"><span style="font-size:large"><i><font face="garamond, serif"><b><font color="#FF6600">Hilmy</font></b></font></i></span><br>
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